The remains of a Russian airliner which crashed is seen in central Sinai near El Arish city, north Egypt on 31 OctoberReuters

Russia's security chief has admitted that a "terror act" brought down Russian Metrojet flight 9268 in Egypt's Sinai killing all 224 people on board.

FSB chief Alexander Bortnikov said a bomb went off on the plane after traces of explosives were found in the wreckage. The Russian A321 plane was allegedly blown up by a homemade explosive device and up to 1.5 kilos of TNT were believed to be on board.

Russian president Vladimir Putin promised to find perpetrators "in every corner of the planet and punish them."

The FSB also offered a £33m reward to catch the people responsible for the bombing.